Rachel Lola Ben-Alon will present her PhD thesis defense, “Earthen Building: Perception, Environmental LCA, and Policy Analysis,” as a candidate of the PhD of Architecture–Engineering–Construction Management on Tuesday 04 February at 12:00pm in MMCH 107.
Title: “Earthen Building: Perception, Environmental LCA, and Policy Analysis”
By Rachel Lola Ben-Alon, PhD-AECM Candidate
Date: Tuesday, 04 February 2020
Time: 12:00-2:00pm
Location: MMCH 107
PhD Advisory Committee
Professor Vivian Loftness, Chair
School of Architecture, Carnegie Mellon UniversityDr. Erica Cochran Hameen
School of Architecture, Carnegie Mellon UniversityProfessor Kent A. Harries
Civil/Environmental Engineering, University of Pittsburgh
Abstract
The vast majority of modern buildings are constructed from highly processed, and often toxic, materials such as synthetic insulation and concrete. Making and processing conventional building materials account for major environmental impacts and were shown to be draining our natural resources. One prominent solution to this problem is using minimally processed and low-carbon building materials that offer excellent thermal properties. Specifically, earthen building materials such as clay-rich soil are readily available, community engaging, and biodegradable. By combining earthen materials in different methods, such as rammed-earth, cob, and compressed earth blocks (CEB), these assemblies provide high thermal inertia and high hygrothermal performance, resulting in optimal indoor environment for occupants’ comfort and health. Despite their advantages, earthen materials have not been implemented comprehensively for various reasons. First, earthen materials technical data varies significantly, making it challenging to quantify their true performance for different climates. Second, there is a broad and often negative perception that earthen materials are “poor-man’s materials” and low-tech. Lastly, earthen materials are not comprehensively represented in building codes and standards. In light of the above benefits and gaps, earthen materials are a critical future that need justification, demonstration, and code permission possibilities. The overall goal of this doctoral thesis is to develop performance-based and policy-based assessments that could be used by policy makers and give rise to top-down mainstream implementation of earthen materials in the construction industry. To achieve these goals, this dissertation includes three critical steps: (1) Perception survey and interviews analysis that identify how negative perception on earthen building can be revised, (2) Technical justification of earthen building materials that includes an environmental Life Cycle Assessment (LCA) of earthen materials compared to conventional building materials, and (3) Policy repair analysis for earthen building codes and standards that suggests requirements to developing comprehensive earthen building codes.
The perception surveys show that in order to advance earthen building materials, homeowners and potential homeowners should be provided with health and indoor quality advantages of earthen homes. Policymakers should be equipped with enumerated environmental advantages of earthen materials. Furthermore, the building permitting barrier is shown to be the most influential and critical to overcome, especially for CEBs and rammed earth. The environmental LCA shows that earthen assemblies significantly reduce environmental impacts compared to the benchmark assemblies. Particularly, the embodied energy demand is reduced by 62-71%, the embodied global climate change impacts are reduced by 85-91%, the embodied air acidification is reduced by 79-95%, and the embodied particulate pollution is virtually eliminated. The operational impacts are shown to be highly dependent on the hygrothermal properties and climate zone. Light straw clay is shown to outperform all other assemblies for both arid and temperate climates. Lastly, the policy repair analysis provides strategic solutions to earthen building codes unfamiliarity and under-development, including recommendations to advance permitting processes in the absence of a local earthen building code, motivation for forming a USA national organization for earthen building, as well as a pathway to develop an international comprehensive earthen building code by use of successful precedents from around the world. This doctoral thesis contributes to the development of environmental and policy measures that could be used by policy makers and earthen building advocates in their endeavors to catalyze the use of earthen building in mainstream construction projects. The long-term implications this research hopes to achieve are the catalysis of earthen building construction in mainstream projects through the development of a complete, safe, and user-friendly earthen building representations in building codes worldwide.